1. Field of the Invention
The present invention relates to a method and device for storing stereochemical information about chemical compounds.
2. Prior Art
Chemical compounds have three-dimensional structures by their own nature. When information about these compounds is to be stored in electronic computers, however, various difficulties are encountered since it has to be expressed two-dimensionally. In particular, it is difficult to discriminate compounds which, when rotated in space, afford sterically different structures as well as to identify the compounds which must be stereochemically the same.
A method has, therefore, been employed to describe all of the three-dimensional coordinates of the atoms and to store them. With such a method however, the storage capacity must be tremendously great, involving much redundancy, and the three-dimensional agreements are not necessarily guaranteed.
There has also been proposed a chemical compound registry system by Chemical Abstracts Service in U.S.A., in which only stereodescriptors are involved. With this method, however, the descriptors have no correspondence with each atom in the connection table; i.e., the method cannot meet the requirement of the increasing complicated information related to the stereochemistry. With this method, furthermore, it is difficult to concretely describe which atom is arranged and in what manner. Moreover, with regard to compounds of formulas III and IV that will be mentioned later, the stereodescriptors are different, i.e., (2R, 4S) for III and (2S, 4R) for IV, so that the compounds may be regarded as completely different from each other. To avoid such misjudgement, the structures of the compounds must be checked and corrected manually.